Method and system for welding railroad rails

ABSTRACT

A method of gas shielded arc welding steel railroad rails spaced from each other to define a transverse gap, which method comprising the steps of providing an elongated steel barrier plate wedged into said gap at the bottom of the spaced rails and filling gap above said steel barrier plate with a molten steel from an advancing filler metal electrode by a gas shielded electric arc welding process initiated by an arc between the electrode and the barrier plate.

The present invention relates to a method and system for welding thespaced ends of rails and more particularly welding two spaced railroadrails in the field by an arc welding process.

INCORPORATION BY REFERENCE

Through the years, a tremendous amount of effort have been devoted tojoining spaced railroad rails by some type of butt welding process. Suchefforts have generally proven costly and unsuccessful, due tolimitations of the processes used, the required time for accomplishingthe welding process, the cost of performing the welding process and/orthe inability to obtain successful, long-lasting joints. In DevletianU.S. Pat. No. 4,429,207, the most common electric arc welding process isillustrated wherein the electroslag welding procedure is used to fillthe gaps between spaced railroad rails in the field. This processinvolves filling the gap between the rails with a pool of molten metalcovered by an appropriate slag. To prevent the mass of molten metal fromflowing from the gap between the rails, side molds and a bottom memberare provided that creates a large protrusion of metal below the railsand extending from the actual gap. This prior patent illustrates amodified electroslag welding (ESW) technique which can be used in thefield, where the rails cannot be turned upside down for normal welding.The advantage of electroslag welding over the normal thermite techniquenormally-used today are explained. In this disclosure, the thermiteprocess is revealed to have substantial deficiencies, which are known toresult in numerous failures in the field. This patent is incorporated byreference herein to describe the electroslag welding process even thoughthe process has been abandoned as a practical process because of itsobvious inefficiencies and inability to obtain uniform and successfulwelds in the field. Indeed, this process must deal with large masses ofmolten metal which presents problems in the field.

As an alleged advantage over the electroslag process, the combination ofthe electroslag technique and the gas shielded arc welding technique isdisclosed in Karimine U.S. Pat. No. 5,175,405. This patent employs anautomatic welding process for butt welding the spaced ends of railroadrails using a gas shielded arc welding process in combination with anelectroslag process. The deficiencies of the normally-used thermitewelding technique and the previously attempted enclosed arc weldingtechnique are discussed in detail. As indicated, the thermite techniqueproduces joints which have an unacceptably high failure rate; however,because of the economics, the time and inability to obtain an arcwelding process of success, this thermite process is still the processof choice in the field. A disadvantage of the continuous arc weldingtechnique discussed, as in this patent, is the inability to start thearc and the need for starting and stopping the arc as the weldingprocess is performed. To overcome some of these disadvantages, thispatent discussed the use of a submerged arc process at the bottomportion of the gap between the rails to start positively the weldingprocess for subsequent and continuous arc welding. Karimine U.S. Pat.No. 5,175,405 is incorporated by reference herein to disclose thedeficiencies of the therrnite process, the enclosed arc weldingtechnique and the submerged arc technique, all of which have beenattempted and have not been successful in the field. The solutionsuggested by Karimine U.S. Pat. No. 5,175,405 is the use of a gasshielded arc welding technique in combination with an electroslagwelding process wherein the gas shielded arc welding technique is usedat the base of the gap to overcome the disadvantages of the previousattempts to use total electroslag welding. However, this process ofusing a gas shielded arc at the bottom of a gap could not be successfulin the field due to the fact that there is no technique that will ensureaccurate starting and depositing the first layer of the filler metal atthe bottom of the gap.

The two patents incorporated by reference illustrate the deficiencies ofthe prior art to which the present invention is directed wherein acombination of various types of arc welding processes have beenattempted without success. Consequently, the admittedly deficientthermite process is the only process used extensively for providingmolten metal between the spaced rails for joining such rails in thefield.

BACKGROUND OF THE INVENTION

Railroad rails must be installed and repaired by joining ends of therails while they are in use or assembled for use in the field. Thejoining process results in a joint between the rails which has a highstrength, can be adjusted metallurgically, will not crack and can beeconomically formed in a very short time. As a criteria for such weldingprocess, the process must be performed in substantially less than 45minutes or such process will cause a delay or rerouting of traintraffic. Two processes are now used for joining the rails in the field.The first process is the thermite technique wherein the spaced rails aresurrounded by an appropriate sand mold and steel is melted and pouredinto the mold to fill the gap between the spaced rails. As the moltenmetal solidifies, the rails are joined; however, this process, which isuniversally used, has a failure rate that has been reported to be ashigh as 75%. In addition, the rails must be melted by the molten steelpoured into the gaps between the rails. This melting requirement is notconsistently met and also contributes to the failure of the jointsproduced in the field by the thermite process. To drastically decreasethe deficiencies of the universally used thermite process, wherein steelis cast into the gaps between the rails, the ends of the rails may bejoined by a flash butt welding process where the ends of the rails aredriven together by tremendously high forces while electricity is passedbetween the rails. This causes the ends of the rails to become moltenand pressure welded together. This process drastically reduces thefailure rate of the joint to less than 10%. However, the flash buttwelding process is best performed on rails in a manufacturing facilitywhere the rails are not fixed on ties and can be forced together bystationary hydraulic equipment. To overcome the disadvantage of theuniversally used thermite process, the flash butt welding process hasbeen modified for use in the field. However, the time for the weldingprocess is substantially higher than the thermite process, since therails must be stretched during the hydraulic forcing step, which steprequires disconnecting one or both of the rails from the ties. Thismanual procedure must be reversed after the welding process hasoccurred, which is extremely time consuming.

Flash butt welding of rails consumes a portion of the rails which causesdifficulties after the welding process has been completed. Also,sections of rails may have to be spliced into the rail to provide thenecessary rail material for the weld.

In addition, it is deficient to transport the hydraulic equipment neededto create the tremendous pressure between the rails to remote locationsas required in the field. The butt welding process also produces a flasharound the periphery of the joined rails which must be sheared off andthen ground to allow a smooth operation and also to prevent stressconcentrations in the joint during use. Even though the flash buttwelding process drastically reduces the rate of failure of the jointsmade in the field, the thermite process is still used because it can bedone rapidly by merely putting a mold around the gap between the spacedrails. The process does not require large hydraulic equipment and isrelatively inexpensive. The failure rate is addressed by againperforming the thermite process when a joint has failed. In doing this,a large section of the rail must be cut and a new section of rail isinserted in the open area. Consequently, a failed thermite jointnormally results in the need for two replacement theimite joints, withtheir propensity for failure. As can be seen, even though the thermiteprocess is universally used, there is a substantial need for someprocess which will join the rails in the field, which process has a lowfailure rate, but has the advantages associated with the thermiteprocess. This need has existed for many years. Arc welding processeshave been tried periodically, such as electroslag, continuous arcwelding and submerged arc welding and combinations thereof. None ofthese processes has been successful because they use impractically largeequipment, take an unacceptably long time to weld and finish grind, andhave not resulted in acceptable failure rates. The arc welding process,especially in the lower part of the gap between the rails, has beeninconsistent. In addition, these prior attempts to use arc welding forjoining the ends of spaced railroad rails were expensive, requiredcomplex equipment and demanded a substantial time to prepare for thewelding process and actually performing the welding process. Such timeis not available in field welding of rails.

THE PRESENT INVENTION

The present invention relates to a method and system for using gasshielded arc welding to join the spaced ends of railroad rails in thefield, which method and system result in an economical, rapid andmechanically and metallurgically sound technique.

Railroad rails have a somewhat standard cross-sectional shape involvinga lower base with a support bottom, which bottom is relatively wide toallow the rail to be placed in a stable position on spaced ties. Abovethe base is a vertically extending web that merges into an upperwheel-engaging head. This head is often hardened to provide better wearresistance as the wheels of the train roll over the rails. Hardness inthe head area is especially important in curved track sections sincethere is a slipping action between the wheels and the rails due to thesolid axle construction between transversely spaced railroad wheels. Inaddition, the rails must have a smooth head to prevent vibration of carspassing over the rails. This need to reduce vibration has caused asubstantial increase in the desire to actually butt weld the rails inhigh speed, high weight rail systems. In the distant past, the railswere not welded together, which created the characteristic vibration oftrains passing over the rails. With the advent of the high speed, highweight and high tech railway systems, the rails must be joined togetheras a continuous rail which has increased the demand for joiningprocesses performed in the field to which the present invention is animprovement. The invention overcomes the disadvantages of the thermitetechnique and the flash butt weld technique.

In accordance with the present invention, the ends of rails to be joinedare spaced from each other to define a gap having a lower opening. Thisgap has a width for the purposes of gas shielded arc welding byproviding filler metal and gun in the gap. In accordance with theinvention, an elongated steel barrier plate with a length generallycorresponding to the width of the rails at the base and a width greaterthan the width of the gap, is wedged between the rails at the bottom ofthe gap. Thus, in the lower portions of the base areas of the gap, thissteel barrier plate is driven to span between the spaced rails. Thiswedging action causes a contact between the barrier plate and the tworails, both of which are grounded. After wedging the barrier plate intoposition at the bottom of the gap between the rails, the gap is filledwith molten metal by the gas shielded electric arc welding process whichis initiated by bringing a welding gun downwardly until the electrodefiller metal contacts the barrier plate. The plate has a thickness ofgenerally one-eight inch and in the range of 0.050 to 0.300 inches.Since this lower barrier plate is tightly wedged between the rails atthe bottom of the gap, the welding process is started by bringing thefiller metal electrode into contact with the barrier plate. The welding,thus, takes place on the top of the relatively substantial fixed barrierplate in accordance with standard gas welding technique. In the lowerportion, the gas welding technique is a constant voltage spray arcwelding. This process allows for high heat and penetration at the lowerlayer of weld metal. The electrode is a high strength, low alloymetal-cored electrode, wherein the core material provides the neededalloy metals. The metal cored electrode is shielded with an appropriateshielding gas. In practice, the metal-cored electrode is a MC 1100Outershield electrode with a gas shielding of 95% Argon and 5% of CarbonDioxide or Oxygen. The core metal of the electrode is selected to matchthe metal forming the spaced rails to give the necessary yield strength.The gas shielding is provided around the advancing metal-cored electrodein accordance with standard practice in either the spray mode or asubsequently used pulsed mode of arc welding. In this process, verylittle slag is created, which was a problem with the submerged arc andelectroslag processes. Such slag created in those processes can resultin inclusions in the metal, especially at the interface between themolten metal and the ends of the rails. These inclusions cause failures.

The present invention utilizes a gas shielded arc welding process ineither the pulsed mode or a constant voltage spray mode, with the spraymode being used at the bottom of the gap adjacent the novel barrierplate wedged between the spaced rails. The invention uses a highperformance digitally controlled power supply with a complex, high speedwaveform control. In practice, a Lincoln Electric Powerwave 450 powersupply is provided which has the capability of switching immediatelybetween constant voltage spray welding and then an appropriatelycontrolled pulsed welding process. In each instance, the welding processof the present invention is a gas shielded electric arc welding processwhich produces the high heat necessary to provide a sound metalinterface between the ends of the rails and the weld metal produced bythe metal-cored electrode as it advances towards the pool of moltenmetal in accordance with standard welding practice. Before performingthis operation, the rails are preheated to a temperature of about 900°F. The first layer of weld metal is laid while consuming the barrierplate wedged between the rails by moving the electrode across the gapwhile it is moving transversely along the gap. The root pass is appliedby the spray welding process, as are the next several layers to allowhigh penetration and a high heat in the large area at the base of therails. Thereafter, the power supply is switched to a pulsed weldprocess. Additional passes are made to fill in the area between therails at the lower base of the rails. After the first or second passes,the wedged barrier plate is no longer a factor since the molten metalabove the plate is solidified. When the welding process approaches theweb portion of the rails, contoured copper shoes are used to enclose thegap so that the gap now provides an enclosed cavity. The cavity isfilled by continuing the shielded gas welding process, which process isconverted back to the constant voltage spray mode to penetrateeffectively. This arc welding process continues beyond the web to thehead of the rails. In practice, the pulsed mode of operation is employedto provide transition areas between the spray mode of constant voltagewelding, which process is used at the major part of both the head andweb and at the starting part of the lower base. It has been found thatgood results can be obtained by switching between a spray mode and apulsed mode of operation. The pulse arc mode of welding is used for heatinput control during certain portions of the total welding process.

As so far described, a gas shielded electric arc welding process fillsthe gap between the spaced rails, which process is made possible by theuse of a lower barrier plate actually wedged between the two rails atthe bottom of the gap between the rails. This barrier plate is formed ofsteel and has a thickness of between 0.050 to 0.300 inches. The lateraledges of the plate are chamfered to produce about a 0.030 inch verticalcontact ledge. In this manner, the wedging action can deform the edgesof the barrier plate to ensure positive electrical contact between therails and the barrier plate. In practice, the original width of thebarrier plate is greater than the width of the gap between the rails toensure a tight wedging action as the barrier plate is forced into awedged position at the bottom of the gap. The width of the plate is inthe range of 0.010 to 0.025 inches greater than the width of the gap.This causes a distortion of the plate as it is wedged into position andassures a fixed position and electrical contact, which contact isessential to an efficient subsequent arc welding process. In the past,no such starting mechanism was provided for an electric arc weldingprocess used to join the spaced ends of railroad rails.

In accordance with another aspect of the present invention, the novelmethod and system includes a heat insulation element, or ceramic layer,below the barrier plate and overlapping the lower opening of the gap toprevent the arc from penetrating through to the copper whereby the arccould melt a portion of the copper which could cause copper inducedcracking problems. The copper support block is located under the railsfor preventing loss of the molten metal in the gap and is a heat sink toprevent over heating of the weld deposit.

The primary object of the present invention is a provision of a methodand system for gas shielded arc welding of steel railroad rails, whichmethod and system can be performed rapidly in the field and have a lowfailure rate.

Yet another object of the present invention is a provision of a methodand system, as defined above, which method and system employs theconcept of wedging a metal barrier plate in the bottom of the gapbetween the spaced rails to start and control the lower portion of thegas shielded arc welding process used in the method and system of theinvention.

Still another object of the invention is a provision of a barrier plateto be wedged between spaced railroad rails at the bottom of the gapsbetween the rails for the purposes of allowing an efficient and rapidjoining of the rails by a gas shielded arc welding process.

These and other objects and advantages will become apparent from thefollowing description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view of a railroad with rails spaced to define agap ready for joining in the field;

FIG. 2 is a cross-sectional view of the end of the rail with a part ofthe wheel shown for the purposes of illustrating the need for hardnessat the head of the joint between the rails;

FIG. 3 is a side elevational view showing the spaced rails beingconditioned for the start of the method and system of the presentinvention;

FIG. 4 is a cross-sectional view taken generally along line 4--4 of FIG.3;

FIG. 5 is a pictorial view of the novel barrier plate constructed inaccordance with the present invention;

FIG. 6 is a partially cross-sectional view of the barrier plate shown inFIG. 5;

FIG. 7 is a schematic view illustrating characteristics of the novelbarrier plate shown in FIGS. 5 and 6 as it is being wedged into positionbetween the rails;

FIG. 8 is a view similar to FIG. 7 showing the arc welding gun andelectrode at the start of the arc welding process;

FIG. 9 is a top plan view of the gap between the space railsillustrating certain requirements for the metal barrier plate, shown inFIGS. 5 and 6;

FIG. 10 is a top view showing the gap between the space rails with theroot pass or first layer being processed;

FIGS. 11 and 11A are enlarged, partially cross-sectional views showingthe progress of the welding process in the gaps adjacent the base of therails and then starting in the web area of the rails;

FIG. 12 is a partial cross-sectional end view showing a modification ofthe preferred embodiment of the present invention; and,

FIG. 13 is a side elevational view of the rail showing portions of thegap which are welded by constant voltage spray welding and by pulsedwelding in the preferred embodiment of the present invention.

THE PREFERRED EMBODIMENT

Referring now to the figures wherein the drawings are for the purpose ofillustrating the preferred embodiment of the invention only and not forthe purpose of limiting same, FIG. 1 shows a railroad rail A laid onright-of-way bed B and including rails 10, 12 to be joined to form acontinuous welded rail (CWR) and supported on bed B by ties 20, steelsupport caps 30 and spikes 32. Rails 10, 12 are spaced to define a gap gwhich is to be filled by molten metal to join the two rails 10, 12together as a continuous rail in the field, as opposed to a plantassembly of continuous rail. Gap g can be the gap between two sectionsof rail to be repaired or the gap between two sections of rail which areto be initially installed as a continuous welded rail system. If the gapg is used for repairing, it is sometimes necessary to cut the rails andinsert a long rail section. This process is used for repairing railswhich have fractures, joints which have fractured or joints which aredefective. In all instances, the two spaced rails 10, 12 are separatedby a gap g which is generally 1.00 inches. The pictorial representationin FIG. 2 shows rail 10 which has a standard profile or cross-sectionincluding a lower base 40 which is quite wide and includes a supportbottom 42 for stabilizing the rail on ties 20 to support the weight oftrains passing along the rails. Base 40 has two upwardly angled topportions 44, 46 that merge into a vertically extending web 50 having alower fillet 52 and an upper fillet 54. The upper fillet merges intohead 60 having a large body portion 62 and an upper wheel supportsurface 64, known as the rail crown, which surface area receives arolling wheel W having a cylindrical rim 70 and a disc 72 that preventsthe wheel from moving to the left on the head 60 as the wheel rollsalong the rail. In view of the contact of the wheel with the side orbody portion 62, and the continuous high weight contact of rim 70 withupper surface 64, head 60 has a normal hardness of Brinell 300 with arange of -60 to +40 on the Brinell Scale. Since the head is hardened,the metal forming the rail, at least in the head portion, must be afairly high alloy steel. The alloy steel used in the filler metal tofill gap g has hardness along the upper portion of the rail in the areaof gap g that meets the rail welding specification in accordance withthe present invention.

In FIG. 3, the elements on rail 12 corresponding to elements on rail 10are indicated by the suffix "a." This same designation will be used inexplaining the copper shoes 100, 110 wherein shoe 100 is draped overrail 10 and shoe 110 is draped over rail 12. Shoe 100 will be describedin detail and the same description applies to shoe 110, wherein thecorresponding elements on shoe 110 corresponding to the elements on shoe100 will be designated with "a." In FIG. 4, shoe 100 includes a topsupport bar 120 allowing hanging shoes 122, 124 formed of heavy copperblocks to be slidable along the head of a rail. The top support bar 120also provides alignment of shoes 122, 124 and maintains spacing of shoe122 from shoe 124 as well as the gap between the shoes and the railsections. Facing inwardly toward the rail cross-section are contourfaces 126, 128, respectively. These faces match the contour of rail 10so that sliding of shoes 100, 110 together at gap g closes the gap toproduce a cavity having a cross-sectional shape of the rails 10, 12. Tostabilize the hanging shoes, alignment pins 130 are provided togetherwith bolts 132, 134 to allow assembly of the heavy copper shoes 122, 124from support bar 120. In operation, the shoes are moved to the positionshown in FIG. 3 to open gap g and allow welding at the lower baseportion of the rails. Thereafter, shoes 100, 110 are moved together toclose the gap to allow welding in the vertically extending web portions50, 50a of rails 10, 12, respectively. As will be explained later, alower block 150 formed of copper, or high copper content alloy, ispositioned under the bottom 42 of rail bases 40, 40a. An uppertransversely extending recess 152 is dimensioned to accommodate aninsulation element in the form of a ceramic layer 154 which spans thebottom portion of gap g under the rails as shown in FIG. 3. To close thebottom of gap g, there is a novel elongated barrier plate P best shownin FIGS. 5, 6 and 7.

In the past, electric arc welding in gap g was attempted, but was notsuccessful because the processes were not consistent in operation anddid not have a support structure for laying the first or second layersof filler metal in gap g. This gap is approximately 1.00 inch toaccommodate a downwardly extending gun carrying an electrode and a gasnozzle such as shown in FIG. 8. In the past, since the gap has to befairly wide to accommodate the welding equipment, there was not auniform and consistent filling of the gap, especially at the bottomportion where it was critical because of the support function of therails. The rails flex and are stressed drastically at base 40. To solvethese problems, the present invention involves the use of plate P shownin FIGS. 5-7. This plate is formed of low carbon steel, since thealloying in the gap is accomplished by the metal powder in the core ofthe electrode used in the arc welding process. This plate has athickness in the range of 0.050 to 0.300 inches. In practice, the platehas a thickness of 0.125 with a width between parallel edges 200, 202being designated as dimension b in FIG. 7. This dimension, in itsoriginal condition, is slightly greater than the width a of gap g.Consequently, plate P must be forced, such as by a hammer, to be wedgedbetween rails 10, 12 at the lowermost portion of the rails, as shown inFIG. 3. This wedging action causes the plate to be swaged to a slightlysmaller final width. This wedging action which swages one or more of theedges 200, 202 of plate P assures electrical contact between plate P andrails 10, 12, which rails are grounded. When in position, plate P restson the top of insulating element 154 located in recess 152 of lowersupport copper block 150. Block 150 provides a lower barrier for moltenmetal being deposited in gap g between rails 10, 12 during the arcwelding process to be explained later. Shown in FIGS. 5 and 6, paralleledges 200, 202 include 30° chamfers 210,212, respectively which areinitiated at about 0.030 inches below the top surface of plate P todefine flat ledges or walls 220, 222, respectively. These walls areswaged against the facing surfaces of rails 10, 12 at the bottom of gapg to form the bottom of a gap to initiate the welding process. Plate Pis forced and wedged into the position shown in FIG. 8 to a rigid, fixedposition.

Referring now to FIG. 8, gas metal arc welding gun 250 has a diameter x,about 1/2 inch, and the gap g has a thickness of 1.00 inch allowingmovement of gun 250 in gap g. Continuously issuing from gun 250 is ametal-cored electrode 260 supported in guide 262 which, in practice, isa high strength low alloy metal cored electrode, typically of theE110C-G type. The wire or electrode can be a Lincoln Electric electrodesold as Outershield MC 1100. As electrode 260 is advancing downward, arcC is created between plate P and electrode 260. This arc may be eitherused for spray or pulsed welding, as will be described later. Ashielding gas G is propelled from passage 264 around electrode guide 262in accordance with standard gas shielded arc welding technology. Wedgingof plate P assures that the grounded rails are in intimate contact withbarrier plate P. The upper surface of a plate is used to strike the arcand the plate itself supports the weld puddle during the first and/orsecond pass of electrode 260 in its progress along the upper surface ofplate P fixed in gap g. This plate supports the arc during the startingoperation. Insulation 154 prevents penetration of the arc to the coppersupport block 150. In this manner, block 150 provides a good heat sink,but does not allow copper migration into the weld. Copper contaminationis prevented by plate P and the use of the lower ceramic layer 154.During the starting of the arc, the arc will not burn through therelatively thick plate P. As the arc moves back and forth between rail10 and rail 12, the arc will move into the area of chamfers 210, 212 atwhich time the arc may penetrate through plate P along the edge 200,202. However, molten weld metal from the metal-cored electrode may flowthrough this portion of the plate P against the lower insulation layeror ceramic layer 154 without causing any problems. Edges 200, 202 arechamfered to allow the wedging action that is necessary to create thetight electrical contact so that there is a superior grounding action atthe plate during the arc welding process. The plate is wedged into thebottom of gap g. The shielding gas G surrounds arc C and the plate Pmaintains the lower barrier for the weld metal. In FIG. 10, it isillustrated that electrode 260 moves back and forth in a serpentinepattern as the electrode passes for the first time over plate P to laythe first or root pass R. The metal from this first pass is maintainedon plate P and forms a molten metal pool joining the bottom portions ofrails 10, 12.

The arc welding process is accomplished by using a digitally controlledinverter welding power source capable of complex high speed waveformcontrol, such as the Lincoln Electric Powerwave 450 Power Supply. Theroot pass R is accomplished by a constant voltage spray welding processfor high heat and high penetration in the root. As illustrated in FIG.11, several layers are laid transversely across gap g in the lowerportion of the gaps between bases 40, 40a of rails 10, 12, respectively.After several layers of metal have been deposited by the constantvoltage process, the power supply is switched to a pulsed mode ofoperation and lays additional layers, as shown again in FIG. 11. Thiscovers the base welding operation of gap g. Thereafter, as shown in FIG.11A, shoes 100, 110 are moved to enclose the gap g at the web portionand head portion of rails 10, 12. As shown in FIG. 3, bars 120, 120a areoffset transversely along the rails. This produces an upper openingbetween shoes 100, 110 to allow continued use of gun 150 in the weldingprocess. This welding process can shift between constant voltage sprayor the more rapid pulsed mode of operation. In both instances, theprocess is a gas shielded arc welding process to fill the gap withfiller metal from electrode 260. The metal in the core is selected toproperly alloy the filler metal in gap g to produce the desired strengthand metallurgical characteristics of the weld joint.

The welding process, as used in practice, is schematically illustratedin FIG. 13. A pulsed mode of operation is used adjacent the angled topportions 44, 46 of bases 40, 40a. In a like manner, a pulsed mode ofoperation is used in the area of fillet 54 and at the top surface 64 ofhead 60. The spray mode of operation is used at the bottom for startingroot pass of the process to assure proper initiation of the weldingprocess and joining of the rails at the root in gap g. Combinations ofthe spray mode and pulsed mode can be used or the spray mode can be usedfor the total process. The spray mode is used at novel plate P.

Even though the facing surfaces of rails 10, 12 are flat, it is possiblethat there may a slight curvature in one or more of the surfaces. Thisconcept is schematically illustrated in FIG. 9 wherein a gap e iscreated between plate P and the end surface of rail 10. The limitationof the present invention is that the diameter d of electrode 260, whichin practice is approximately 1/16 inch, must be substantially more thangap e so that the arc created by electrode 260 will not merely passdownwardly through insulation barrier or element 154. Even with thisslight variation, there is still proper contact between the rail orrails for the purposes of grounding plate P to assure intimateelectrical continuity between plate P and the grounded rails. Thisillustration is only presented for the purposes of discussing theconcept that the plate P provides a barrier between the arc C and thelower support structure below gap g.

A slight modification of the invention is illustrated in FIG. 12 whereinsupport 150 has end plate 300 extending upwardly adjacent the lateralportions of bases 40, 40a of the rails. Insulation cloth, or ceramiclayer, 154 has an elongated portion 1 54a that moves upwardly along endplates 300 to provide an outermost dam or barrier for the molten fillermetal deposited in lower portion of gap g before shoes 100, 110 aremoved together for welding in the web area and head area of gap g.

The present invention has no slag in the filler metal deposited in gapg. It also employs a gas shield process which process can be convertedbetween spray mode of operation and pulsed mode of operation by using avariety of power supplies available in the welding field. It has beenfound that this welding process produces a sound weld with failure ratesthat rival the failure rates of the flash butt weld technique. Barrierplate P is consumed; thus, it is part of the molten metal at the rootportion of gap g. The alloy material does not need to be provided byplate P since the metal-cored electrode carries the alloying metals inits core.

Having thus defined the invention, the following is claimed:
 1. A methodof gas shielded arc welding steel railroad rails each having a lowerbase with a support bottom having a given width, a vertically extendingweb and an upper wheel engaging head, said rails being spaced from eachother to define a transverse gap to be filled with steel to join saidrails wherein said gap has a lower opening, lateral, verticallyextending distal openings and a selected width, said method comprisingthe steps of:(a) providing an elongated steel barrier plate with alength corresponding to said given width of said lower bases, a widthgreater than said selected width of said gap and a nominal thickness;(b) wedging said barrier plate into said gap at the bottom of said basesof said spaced rails; and, (c) filling said gap above said steel barrierplate with a molten steel from an advancing filler metal electrode by agas shielded electric arc welding process initiated by an arc betweensaid electrode and said barrier plate.
 2. A method as defined in claim 1including the step of:(d) locating a heat insulation element below saidbarrier plate and overlapping said lower opening of said gap and saidsupport bottoms of said bases of said spaced rails.
 3. A method asdefined in claim 2 including the step of:(e) providing a metal blockspanning lower opening of said gap and engaging said support bottoms ofsaid bases, said block having an upwardly facing recess to accommodatesaid insulation element.
 4. The method as defined in claim 3 includingthe step of:(f) moving side molds over said lateral, verticallyextending distal openings of said gap after said filing step has filledsaid gap with filler metal at said bases.
 5. A method as defined inclaim 3 wherein said block is formed primarily from copper.
 6. Themethod as defined in claim 2 including the step of:(e) moving side moldsover said lateral, vertically extending distal openings of said gapbefore said filing step is completed.
 7. A method as defined in claim 2wherein said heat insulation element is ceramic.
 8. A method as definedin claim 2 wherein said heat insulation element is a sheet of ceramiccloth.
 9. A method as defined in claim 2 wherein said heat insulationelement has a thickness in the range of 2.0 to 10.0 mm.
 10. The methodas defined in claim 1 including the step of:(d) moving side molds oversaid lateral, vertically extending distal openings of said gap aftersaid filing step has filled said gap with filler metal at said bases.11. The method as defined in claim 1 wherein said gas shielded electricarc welding process of said filling step is a multipass arc weldingprocess.
 12. The method as defined in claim 1 wherein said gas shieldedelectric arc welding process of said filling step is an arc weldingprocess including the step of moving the electrode in a serpentine pathas said electrode traverses said gap.
 13. A method as defined in claim12, wherein said serpentine path of said electrode forms aserpentine-shaped weld bead.
 14. A method as defined in claim 13 whereinsaid serpentine-shaped weld bead including a root weld bead.
 15. Themethod as defined in claim 1 wherein said gas shielded electric arcwelding process of said filling step is primarily a multipass spraytransfer process.
 16. The method as defined in claim 1 wherein said gasshielded electric arc welding process of said filling step is acombination of a multipass spray transfer process and a pulsed weldingprocess with said spray transfer process being used at the bottom ofsaid gap.
 17. The method as defined in claim 1 wherein said gas shieldedelectric arc welding process of said filling step is a multipass spraytransfer process at least at the bottom of said gap and in the area ofsaid gap defined by said webs of said spaced rails.
 18. A method asdefined in claim 1 wherein said elongated steel barrier plate is formedfrom low carbon steel.
 19. A method as defined in claim 1 wherein saidelongated steel barrier plate has a thickness in the range of 0.050 to0.300 inches.
 20. A method as defined in claim 1 wherein said elongatedsteel barrier plate has lateral edges which are chamfered.
 21. A methodas defined in claim 1 wherein said elongated steel barrier plate has anoriginal width at least about 0.010 inches greater than said selectedwidth of said gap.
 22. A method as defined in claim 1 wherein saidelongated steel barrier plate has an original width at least about0.010-0.025 inches greater than said selected width of said gap.
 23. Asystem of gas shielded arc welding steel railroad rails each having alower base with a support bottom having a given width, a verticallyextending web and an upper wheel engaging head, said system comprisingmeans for holding said rails spaced from each other to define atransverse gap to be filled with steel to join said rails wherein saidgap has a lower opening, lateral, vertically extending distal openingsand a selected width; an elongated steel barrier plate with a lengthcorresponding to said given width of said lower bases, a width greaterthan said selected width of said gap and a nominal thickness, saidbarrier plate being located at the bottom of said bases of said spacedrails to close said lower opening; and welding means for filling saidgap above said iron barrier plate with a molten steel, said weldingmeans including an advancing filler metal electrode.
 24. A system asdefined in claim 23 including a heat insulation element below saidbarrier plate and overlapping said lower opening of said gap and saidsupport bottoms of said bases of said spaced rails.
 25. A system asdefined in claim 24 including a metal block spanning lower opening ofsaid gap and engaging said support bottoms of said bases, said blockhaving an upwardly facing recess to accommodate said insulation element.26. The system as defined in claim 23 including side molds over saidlateral, vertically extending distal openings of said gap.
 27. A systemas defined in claim 23 wherein said elongated steel barrier plate isformed from low carbon steel.
 28. A system as defined in claim 23wherein said elongated steel barrier plate has a thickness in the rangeof 0.050 to 0.300 inches.
 29. A system as defined in claim 23 whereinsaid elongated steel barrier plate has lateral edges which arechamfered.
 30. A system as defined in claim 23, wherein said weld meansincluding a serpentine advancement of said filler metal electrode.
 31. Asystem as defined in claim 30, wherein said welding means forms aserpentine-shaped weld bead.
 32. A system as defined in claim 31,wherein said serpentine-shaped weld bead including a root weld bead.